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Jiang J, Xiong F, Sun L, Chen H, Zhu M, Xu W, Zhang J, Zhu Z. Reversible Amorphous-Crystalline Phase Transformation in an Ultrathin van der Waals FeTe System. ACS APPLIED MATERIALS & INTERFACES 2023; 15:47661-47668. [PMID: 37783452 DOI: 10.1021/acsami.3c07765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Searching for new phase-change materials for memory and neuromorphic device applications and further understanding the phase transformation mechanism are attracting wide attention. Phase transformation from the amorphous phase to the crystal phase has been unraveled in iron telluride (FeTe) bulk film deposited by pulsed laser deposition, recently. However, the van der Waals-layered feature of FeTe in the crystal form was not noted, which will benefit the scaling of the memory devices and shine light on phase-change heterostructures or interfacial phase-change materials. Moreover, the demonstration of advanced memory or neuromorphic device applications is lacking. Here, we investigate the phase transformation of FeTe starting from mechanically exfoliated van der Waals layers from a bulk single crystal. Surficial amorphization is revealed at the surface layers of FeTe flakes after exfoliation under ambient conditions, which could be transformed back to the crystalline phase with laser irradiation or heating. The conductance drop of the flake devices near 400 K verifies the phase transformation electrically. Memristor behavior of the amorphous surface in FeTe has been further demonstrated, proving the reversibility of the phase transformation and shining light on the possible applications of neuromorphic devices.
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Affiliation(s)
- Jinbao Jiang
- College of Advanced Interdisciplinary Studies & Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Feng Xiong
- College of Advanced Interdisciplinary Studies & Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Linfeng Sun
- School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Haitao Chen
- College of Advanced Interdisciplinary Studies & Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Mengjian Zhu
- College of Advanced Interdisciplinary Studies & Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Wei Xu
- College of Advanced Interdisciplinary Studies & Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Jianfa Zhang
- College of Advanced Interdisciplinary Studies & Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Zhihong Zhu
- College of Advanced Interdisciplinary Studies & Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
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Zhang W, Zhang H, Sun S, Wang X, Lu Z, Wang X, Wang JJ, Jia C, Schön CF, Mazzarello R, Ma E, Wuttig M. Metavalent Bonding in Layered Phase-Change Memory Materials. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2300901. [PMID: 36995041 DOI: 10.1002/advs.202300901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/04/2023] [Indexed: 05/27/2023]
Abstract
Metavalent bonding (MVB) is characterized by the competition between electron delocalization as in metallic bonding and electron localization as in covalent or ionic bonding, serving as an essential ingredient in phase-change materials for advanced memory applications. The crystalline phase-change materials exhibits MVB, which stems from the highly aligned p orbitals and results in large dielectric constants. Breaking the alignment of these chemical bonds leads to a drastic reduction in dielectric constants. In this work, it is clarified how MVB develops across the so-called van der Waals-like gaps in layered Sb2 Te3 and Ge-Sb-Te alloys, where coupling of p orbitals is significantly reduced. A type of extended defect involving such gaps in thin films of trigonal Sb2 Te3 is identified by atomic imaging experiments and ab initio simulations. It is shown that this defect has an impact on the structural and optical properties, which is consistent with the presence of non-negligible electron sharing in the gaps. Furthermore, the degree of MVB across the gaps is tailored by applying uniaxial strain, which results in a large variation of dielectric function and reflectivity in the trigonal phase. At last, design strategies are provided for applications utilizing the trigonal phase.
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Affiliation(s)
- Wei Zhang
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Hangming Zhang
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Suyang Sun
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Xiaozhe Wang
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Zhewen Lu
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Xudong Wang
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Jiang-Jing Wang
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Chunlin Jia
- School of Microelectronics, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Carl-Friedrich Schön
- Institute of Physics IA, JARA-FIT, RWTH Aachen University, 52074, Aachen, Germany
| | | | - En Ma
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Matthias Wuttig
- Institute of Physics IA, JARA-FIT, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI 10), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
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Chen Z, Sun M, Li H, Huang B, Loh KP. Oscillatory Order-Disorder Transition during Layer-by-Layer Growth of Indium Selenide. NANO LETTERS 2023; 23:1077-1084. [PMID: 36696459 DOI: 10.1021/acs.nanolett.2c04785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
It is important to understand the polymorph transition and crystal-amorphous phase transition in In2Se3 to tap the potential of this material for resistive memory storage. By monitoring layer-by-layer growth of β-In2Se3 during molecular beam epitaxy (MBE), we are able to identify a cyclical order-disorder transition characterized by a periodic alternation between a glassy-like metastable subunit cell film consisting of n < 5 sublayers (nth layers = the number of subunit cell layers), and a highly crystalline β-In2Se3 at n = 5 layers. The glassy phase shows an odd-even alternation between the indium-cluster layer (n = 1, 3) and an In-Se solid solution (n = 2, 4), which suggests the ability of In and Se atoms to diffuse, aggregate, and intermix. These dynamic natures of In and Se atoms contribute to a defect-driven memory resistive behavior in current-voltage sweeps that is different from the ferroelectric switching of α-In2Se3.
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Affiliation(s)
- Zhi Chen
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology (ICL-2D MOST), Shenzhen University, Shenzhen518060, People's Republic of China
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, People's Republic of China
| | - Mingzi Sun
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, 999077, People's Republic of China
| | - Haohan Li
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore117543, Singapore
| | - Bolong Huang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, 999077, People's Republic of China
- Research Centre for Carbon-Strategic Catalysis, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, 999077, People's Republic of China
| | - Kian Ping Loh
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology (ICL-2D MOST), Shenzhen University, Shenzhen518060, People's Republic of China
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore117543, Singapore
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR999077, People's Republic of China
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Liu C, Zheng Y, Xin T, Zheng Y, Wang R, Cheng Y. The Relationship between Electron Transport and Microstructure in Ge 2Sb 2Te 5 Alloy. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:582. [PMID: 36770543 PMCID: PMC9919368 DOI: 10.3390/nano13030582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/20/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
Phase-change random-access memory (PCRAM) holds great promise for next-generation information storage applications. As a mature phase change material, Ge2Sb2Te5 alloy (GST) relies on the distinct electrical properties of different states to achieve information storage, but there are relatively few studies on the relationship between electron transport and microstructure. In this work, we found that the first resistance dropping in GST film is related to the increase of carrier concentration, in which the atomic bonding environment changes substantially during the crystallization process. The second resistance dropping is related to the increase of carrier mobility. Besides, during the cubic to the hexagonal phase transition, the nanograins grow significantly from ~50 nm to ~300 nm, which reduces the carrier scattering effect. Our study lays the foundation for precisely controlling the storage states of GST-based PCRAM devices.
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Affiliation(s)
- Cheng Liu
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Yonghui Zheng
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China
- Chongqing Key Laboratory of Precision Optics, Chongqing Institute of East China Normal University, Chongqing 401120, China
| | - Tianjiao Xin
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Yunzhe Zheng
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Rui Wang
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Yan Cheng
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China
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5
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Reflective Terahertz Metasurfaces Based on Non-Volatile Phase Change Material for Switchable Manipulation. PHOTONICS 2022. [DOI: 10.3390/photonics9080508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Recently, metasurfaces have been investigated and exploited for various applications in the THz regime, including modulators and detectors. However, the responsive properties of the metasurface in THz stay fixed once the fabrication process is complete. This limitation can be modified when integrating the phase change material (PCM), whose states are switchable between crystalline and amorphous, into the metasurface structure. This characteristic of the PCM is appealing in achieving dynamic and customizable functionality. In this work, the reflective metasurface structure is designed as a hexagonal unit deposited on a polyimide substrate. The non-volatile PCM chosen for the numerical study is germanium antimony tellurium (GST). Our proposed phase change metasurface provides two resonant frequencies located at 1.72 and 2.70 THz, respectively; one of them shows a high contrast of reflectivity at almost 80%. The effects of geometrical parameters, incident angles, and polarization modes on the properties of the proposed structure are explored. Finally, the performances of the structure are evaluated in terms of the insertion loss and extinction ratio.
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Bian H, Goh YY, Liu Y, Ling H, Xie L, Liu X. Stimuli-Responsive Memristive Materials for Artificial Synapses and Neuromorphic Computing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2006469. [PMID: 33837601 DOI: 10.1002/adma.202006469] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/03/2020] [Indexed: 06/12/2023]
Abstract
Neuromorphic computing holds promise for building next-generation intelligent systems in a more energy-efficient way than the conventional von Neumann computing architecture. Memristive hardware, which mimics biological neurons and synapses, offers high-speed operation and low power consumption, enabling energy- and area-efficient, brain-inspired computing. Here, recent advances in memristive materials and strategies that emulate synaptic functions for neuromorphic computing are highlighted. The working principles and characteristics of biological neurons and synapses, which can be mimicked by memristive devices, are presented. Besides device structures and operation with different external stimuli such as electric, magnetic, and optical fields, how memristive materials with a rich variety of underlying physical mechanisms can allow fast, reliable, and low-power neuromorphic applications is also discussed. Finally, device requirements are examined and a perspective on challenges in developing memristive materials for device engineering and computing science is given.
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Affiliation(s)
- Hongyu Bian
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Yi Yiing Goh
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 119077, Singapore
| | - Yuxia Liu
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
- Center for Functional Materials, National University of Singapore Suzhou Research Institute, Suzhou, 215123, China
| | - Haifeng Ling
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts and Telecommunications, Nanjing, 210023, China
| | - Linghai Xie
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts and Telecommunications, Nanjing, 210023, China
| | - Xiaogang Liu
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
- Center for Functional Materials, National University of Singapore Suzhou Research Institute, Suzhou, 215123, China
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7
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Zaytseva YS, Borgardt NI, Prikhodko AS, Zallo E, Calarko R. Electron Microscopy Study of Surface Islands in Epitaxial Ge3Sb2Te6 Layer Grown on a Silicon Substrate. CRYSTALLOGR REP+ 2021. [DOI: 10.1134/s1063774521030317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Nurmamat M, Okamoto K, Zhu S, Menshchikova TV, Rusinov IP, Korostelev VO, Miyamoto K, Okuda T, Miyashita T, Wang X, Ishida Y, Sumida K, Schwier EF, Ye M, Aliev ZS, Babanly MB, Amiraslanov IR, Chulkov EV, Kokh KA, Tereshchenko OE, Shimada K, Shin S, Kimura A. Topologically Nontrivial Phase-Change Compound GeSb 2Te 4. ACS NANO 2020; 14:9059-9065. [PMID: 32628444 DOI: 10.1021/acsnano.0c04145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Chalcogenide phase-change materials show strikingly contrasting optical and electrical properties, which has led to their extensive implementation in various memory devices. By performing spin-, time-, and angle-resolved photoemission spectroscopy combined with the first-principles calculation, we report the experimental results that the crystalline phase of GeSb2Te4 is topologically nontrivial in the vicinity of the Dirac semimetal phase. The resulting linearly dispersive bulk Dirac-like bands that cross the Fermi level and are thus responsible for conductivity in the stable crystalline phase of GeSb2Te4 can be viewed as a 3D analogue of graphene. Our finding provides us with the possibility of realizing inertia-free Dirac currents in phase-change materials.
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Affiliation(s)
- Munisa Nurmamat
- Department of Physical Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
- Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
| | - Kazuaki Okamoto
- Department of Physical Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
| | - Siyuan Zhu
- Department of Physical Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
| | - Tatiana V Menshchikova
- Tomsk State University, 634050 Tomsk, Russia
- Departamento de F́ısica de Materiales UPV/EHU, CFM-MPC UPV/EHU, 20080 San Sebastían/Donostia, Basque Country, Spain
| | - Igor P Rusinov
- Tomsk State University, 634050 Tomsk, Russia
- St. Petersburg State University, Universitetskaya nab., 7/9, 199034 St. Petersburg, Russia
- Departamento de F́ısica de Materiales UPV/EHU, CFM-MPC UPV/EHU, 20080 San Sebastían/Donostia, Basque Country, Spain
| | | | - Koji Miyamoto
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
| | - Taichi Okuda
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
| | - Takeo Miyashita
- Department of Physical Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
| | - Xiaoxiao Wang
- Department of Physical Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
| | - Yukiaki Ishida
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - Kazuki Sumida
- Department of Physical Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
- Materials Sciences Research Center, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan
| | - Eike F Schwier
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
| | - Mao Ye
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Chang Ning Road, Shanghai 200050, China
| | - Ziya S Aliev
- Azerbaijan State Oil and Industry University, AZ1010 Baku, Azerbaijan
- Institute of Physics, ANAS, AZ1143 Baku, Azerbaijan
| | - Mahammad B Babanly
- Institute of Catalysis and Inorganic Chemistry, ANAS, AZ1143, Baku, Azerbaijan
- Baku State University, AZ1148 Baku, Azerbaijan
| | - Imamaddin R Amiraslanov
- Institute of Physics, ANAS, AZ1143 Baku, Azerbaijan
- Baku State University, AZ1148 Baku, Azerbaijan
| | - Evgueni V Chulkov
- St. Petersburg State University, Universitetskaya nab., 7/9, 199034 St. Petersburg, Russia
- Departamento de F́ısica de Materiales UPV/EHU, CFM-MPC UPV/EHU, 20080 San Sebastían/Donostia, Basque Country, Spain
- Donostia International Physics Center (DIPC), 20018 San Sebastían/Donostia, Basque Country, Spain
| | - Konstantin A Kokh
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, Koptyuga pr. 3, Novosibirsk 630090, Russia
- Novosibirsk State University, ul. Pirogova 2, Novosibirsk 630090, Russia
| | - Oleg E Tereshchenko
- A.V. Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent_eva 13, Novosibirsk 630090, Russia
- Novosibirsk State University, ul. Pirogova 2, Novosibirsk 630090, Russia
| | - Kenya Shimada
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
| | - Shik Shin
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - Akio Kimura
- Department of Physical Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
- Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
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Calais T, Valdivia y Alvarado P. Advanced functional materials for soft robotics: tuning physicochemical properties beyond rigidity control. ACTA ACUST UNITED AC 2019. [DOI: 10.1088/2399-7532/ab4f9d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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10
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Lotnyk A, Behrens M, Rauschenbach B. Phase change thin films for non-volatile memory applications. NANOSCALE ADVANCES 2019; 1:3836-3857. [PMID: 36132100 PMCID: PMC9419560 DOI: 10.1039/c9na00366e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 09/17/2019] [Indexed: 06/10/2023]
Abstract
The rapid development of Internet of Things devices requires real time processing of a huge amount of digital data, creating a new demand for computing technology. Phase change memory technology based on chalcogenide phase change materials meets many requirements of the emerging memory applications since it is fast, scalable and non-volatile. In addition, phase change memory offers multilevel data storage and can be applied both in neuro-inspired and all-photonic in-memory computing. Furthermore, phase change alloys represent an outstanding class of functional materials having a tremendous variety of industrially relevant characteristics and exceptional material properties. Many efforts have been devoted to understanding these properties with the particular aim to design universal memory. This paper reviews materials science aspects of chalcogenide-based phase change thin films relevant for non-volatile memory applications. Particular emphasis is put on local structure, control of disorder and its impact on material properties, order-disorder transitions and interfacial transformations.
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Affiliation(s)
- A Lotnyk
- Leibniz Institute of Surface Engineering (IOM) Permoserstr. 15 04318 Leipzig Germany
| | - M Behrens
- Leibniz Institute of Surface Engineering (IOM) Permoserstr. 15 04318 Leipzig Germany
| | - B Rauschenbach
- Leibniz Institute of Surface Engineering (IOM) Permoserstr. 15 04318 Leipzig Germany
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11
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Bulai G, Pompilian O, Gurlui S, Nemec P, Nazabal V, Cimpoesu N, Chazallon B, Focsa C. Ge-Sb-Te Chalcogenide Thin Films Deposited by Nanosecond, Picosecond, and Femtosecond Laser Ablation. NANOMATERIALS (BASEL, SWITZERLAND) 2019; 9:E676. [PMID: 31052395 PMCID: PMC6567795 DOI: 10.3390/nano9050676] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 04/18/2019] [Accepted: 04/23/2019] [Indexed: 12/20/2022]
Abstract
Ge-Sb-Te thin films were obtained by ns-, ps-, and fs-pulsed laser deposition (PLD) in various experimental conditions. The thickness of the samples was influenced by the Nd-YAG laser wavelength, fluence, target-to-substrate distance, and deposition time. The topography and chemical analysis results showed that the films deposited by ns-PLD revealed droplets on the surface together with a decreased Te concentration and Sb over-stoichiometry. Thin films with improved surface roughness and chemical compositions close to nominal values were deposited by ps- and fs-PLD. The X-ray diffraction and Raman spectroscopy results showed that the samples obtained with ns pulses were partially crystallized while the lower fluences used in ps- and fs-PLD led to amorphous depositions. The optical parameters of the ns-PLD samples were correlated to their structural properties.
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Affiliation(s)
- Georgiana Bulai
- Integrated Centre for Environmental Science Studies in the North-East Development Region-CERNESIM, "Al. I. Cuza" University of Iasi, 700506 Iasi, Romania.
| | - Oana Pompilian
- Université de Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers, Atomes et Molécules, CERLA-Centre d'Etudes et de Recherches Lasers et Applications, Lille F-59000, France.
- National Institute for Lasers, Plasma and Radiation Physics, RO-077125 Magurele-Bucharest, Romania.
| | - Silviu Gurlui
- Faculty of Physics, "Al. I. Cuza" University of Iasi, 700506 Iasi, Romania.
| | - Petr Nemec
- Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice, Czech Republic.
| | - Virginie Nazabal
- Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice, Czech Republic.
- Université de Rennes 1, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)⁻UMR 6226, F-35000 Rennes, France.
| | - Nicanor Cimpoesu
- Faculty of Materials Science and Engineering, "Gheorghe Asachi" Technical University of Iasi, 700050 Iasi, Romania.
| | - Bertrand Chazallon
- Université de Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers, Atomes et Molécules, CERLA-Centre d'Etudes et de Recherches Lasers et Applications, Lille F-59000, France.
| | - Cristian Focsa
- Université de Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers, Atomes et Molécules, CERLA-Centre d'Etudes et de Recherches Lasers et Applications, Lille F-59000, France.
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12
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Singh J, Singh G, Kaura A, Tripathi S. Effect of gradual ordering of Ge/Sb atoms on chemical bonding: A proposed mechanism for the formation of crystalline Ge2Sb2Te5. J SOLID STATE CHEM 2018. [DOI: 10.1016/j.jssc.2018.01.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Qian H, Tong H, He MZ, Ji HK, Zhou LJ, Xu M, Miao XS. Observation of carrier localization in cubic crystalline Ge 2Sb 2Te 5 by field effect measurement. Sci Rep 2018; 8:486. [PMID: 29323199 PMCID: PMC5765150 DOI: 10.1038/s41598-017-18964-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 12/12/2017] [Indexed: 11/09/2022] Open
Abstract
The tunable disorder of vacancies upon annealing is an important character of crystalline phase-change material Ge2Sb2Te5 (GST). A variety of resistance states caused by different degrees of disorder can lead to the development of multilevel memory devices, which could bring a revolution to the memory industry by significantly increasing the storage density and inspiring the neuromorphic computing. This work focuses on the study of disorder-induced carrier localization which could result in multiple resistance levels of crystalline GST. To analyze the effect of carrier localization on multiple resistant levels, the intrinsic field effect (the change in surface conductance with an applied transverse electric field) of crystalline GST was measured, in which GST films were annealed at different temperatures. The field effect measurement is an important complement to conventional transport measurement techniques. The field effect mobility was acquired and showed temperature activation, a hallmark of carrier localization. Based on the relationship between field effect mobility and annealing temperature, we demonstrate that the annealing shifts the mobility edge towards the valence-band edge, delocalizing more carriers. The insight of carrier transport in multilevel crystalline states is of fundamental relevance for the development of multilevel phase change data storage.
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Affiliation(s)
- Hang Qian
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hao Tong
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China. .,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Ming-Ze He
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hong-Kai Ji
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Ling-Jun Zhou
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Ming Xu
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Xiang-Shui Miao
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
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Behrens M, Lotnyk A, Roß U, Griebel J, Schumacher P, Gerlach JW, Rauschenbach B. Impact of disorder on optical reflectivity contrast of epitaxial Ge2Sb2Te5 thin films. CrystEngComm 2018. [DOI: 10.1039/c8ce00534f] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Classification of the optical reflectivity contrasts of single-phase, epitaxial Ge2Sb2Te5 thin films with respect to the vacancy arrangements.
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Affiliation(s)
- Mario Behrens
- Leibniz Institute of Surface Engineering (IOM)
- 04318 Leipzig
- Germany
| | - Andriy Lotnyk
- Leibniz Institute of Surface Engineering (IOM)
- 04318 Leipzig
- Germany
| | - Ulrich Roß
- Leibniz Institute of Surface Engineering (IOM)
- 04318 Leipzig
- Germany
| | - Jan Griebel
- Leibniz Institute of Surface Engineering (IOM)
- 04318 Leipzig
- Germany
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